The present invention has to do with excavating bits which are mounted on tool holders on rotating drums and are used to reduce concrete, asphalt and like formations.
A popular bit which is used on such rotating drums is the rotatable, conical point bit that is more fully described in U.S. Pat. No. 3,519,309, granted to Engle et al and assigned to Kennametal Inc. The Engle et al type bit is usually mounted in the support block which is welded to a rotatable drum and is mounted in such a way that the bit is rotatable within its own support block.
These bits, when mounted on drums, are useful in reducing or planing concrete formations. However, when other formations, such as asphalt, are planed, it is frequently necessary to resort to a bit which has a flat, forwardly facing working portion. When such a bit with a flat, forwardly facing working portion is used, it must be held nonrotatably within its support block in order to perform properly.
Since the drums with the support holders mounted thereon are sometimes switched from one type of work, such as concrete, to another, such as working on asphalt, it is desirable to have a bit which will be interchangeable with the rotatable bit as described by Engle et al, and yet will have a flat, forward working portion and be nonrotatable when held in the same support block.
Prior art bits which have been suggested or tried have used pins or lugs on the bits that necessitated the removal of parent material from the support block in order to engage either the lug or pin member that was used to hold the bit nonrotatably within the block.
It is an object of the present invention to provide a nonrotatable bit which is interchangeable with a support block for a rotatable bit without the weakening of the support block structure.
A further object of the present invention is to provide a nonrotatable bit which is easily and efficiently removable from a rotatable type bit support block.